To achieve luminous colors similar to daylight, metal halide discharge lamps generally contain thallium. By way of example, U.S. Pat. No. 6,107,742 describes a lamp which contains a metal halide fill comprising the metals Cs, Tl, and rare earths, such as Dy, Tm, Ho, and has a luminous color similar to daylight.
Moreover, US-A 2003184231 has disclosed a fill for metal halide lamps which contains V and Mn halide. The fill may additionally contain metal halides comprising the metals Cs, Tl, and rare earths, such as Dy, Tm, Ho. Mn is used as a replacement for Na. The purpose of this is to lower the color temperature.
Finally, DE-A 35 12 757 has disclosed a fill for metal halide lamps which contains a metal silicide, such as V5Si3. The fill additionally contains rare earth or Sc halide and the corresponding rare earth oxyhalide and/or Sc oxide. The silicide in this case acts as a halogen getter.
US-A 2004253897 has disclosed a metal halide lamp with a two-ended outer bulb which surrounds only part of the discharge vessel.